Method for performing a procedure related to AMF registration by UDM in wireless communication system and apparatus for same

ABSTRACT

In one embodiment of the present invention, a method for enabling a UDM (Unified Data Management) to perform a registration related procedure of an AMF (Access and Mobility Management Function) in a wireless communication system comprises the steps of: receiving, by the UDM, a message related to serving AMF registration of a UE, which includes access type information and ID (Identity) information, from a first AMF; transmitting, by the UDM, a deregistration related message to a second AMF when the second AMF exists, wherein the second AMF is registered as a serving AMF of the UE and related to the access type information.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage application under 35 U.S.C. § 371of International Application No. PCT/KR2018/004885, filed on Apr. 26,2018, which claims the benefit of U.S. Provisional Application No.62/501,055, filed on May 3, 2017, and U.S. Provisional Application No.62/491,191, filed on Apr. 27, 2017. The disclosures of the priorapplications are incorporated by reference in their entirety.

TECHNICAL FIELD

The following description relates to a wireless communication system,and more particularly, to a method for enabling UDM (Unified DataManagement) to perform a procedure related to registration of AMF(Access and Mobility Management Function) and a device therefor.

BACKGROUND ART

Wireless communication systems have been widely deployed to providevarious types of communication services such as voice or data. Ingeneral, a wireless communication system is a multiple access systemthat supports communication of multiple users by sharing availablesystem resources (a bandwidth, transmission power, etc.) among them. Forexample, multiple access systems include a Code Division Multiple Access(CDMA) system, a Frequency Division Multiple Access (FDMA) system, aTime Division Multiple Access (TDMA) system, an Orthogonal FrequencyDivision Multiple Access (OFDMA) system, a Single Carrier FrequencyDivision Multiple Access (SC-FDMA) system, and a Multi-Carrier FrequencyDivision Multiple Access (MC-FDMA) system.

DISCLOSURE Technical Problem

An object of the present invention is to provide a method for enabling aUDM to efficiently perform registration of AMF in a 5G mobilecommunication system.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present invention are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present invention could achieve will be more clearlyunderstood from the following detailed description.

Technical Solution

In one embodiment of the present invention, a method for enabling a UDM(Unified Data Management) to perform a registration related procedure ofan AMF (Access and Mobility Management Function) in a wirelesscommunication system comprises the steps of: receiving, by the UDM, amessage related to serving AMF registration of a UE, which includesaccess type information and ID (Identity) information, from a first AMF;transmitting, by the UDM, a deregistration related message to a secondAMF when the second AMF exists, wherein the second AMF is registered asa serving AMF of the UE and related to the access type information.

In one embodiment of the present invention, a UDM (Unified DataManagement) device for performing a registration related procedure of anAMF (Access and Mobility Management Function) in a wirelesscommunication system comprises a transceiver; and a processor, whereinthe processor allows the UDM to receive a message related to serving AMFregistration of a UE, which includes access type information and ID(Identity) information, from a first AMF, and if a second AMF registeredas a serving AMF of the UE, which corresponds to the access typeinformation, exists, the UDM transmits a deregistration related messageto the second AMF.

The UDM may store access type information related to the AMF and the IDinformation.

The UDM may receive a request message related to deletion of UE contextfrom NF, and the request message related to deletion of the UE contextmay include access type information when the NF is the AMF.

If the UDM transmits the deregistration related message due tosubscription withdrawn, it may indicate an access type of thederegistration related message.

If a message for requesting serving AMF information is received from theNF, the serving AMF information related to the access type may betransmitted to the NF, and the message for requesting serving AMFinformation may include access type information.

The method may further comprise the step of receiving a request forrequesting to provide UE reachability information from the NF, whereinthe request for requesting to provide UE reachability information mayinclude access type information.

The UDM may be subscribed to a notification service for UE reachabilityevent by AMF related to the access type.

If information indicating that the UE is reachable is received from theAMF related to the access type, the information indicating that the UEis reachable may be transmitted to the NF.

If the UE performs handover from a 5GS (5G system) to an EPS (EvolvedPacket System), cancel location by the UDM and the HSS may be performedfor AMF of which access type is 3GPP.

If the UE changes a 5GS to an EPS in an idle mode, a cancel locationoperation by the UDM may be performed for AMF of which access type is3GPP.

Advantageous Effects

According to the present invention, a serving AMF and/or relatedinformation may be managed efficiently in a state that AMF may exist peraccess in respect of 3GPP and non-3GPP access.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved through the present invention are not limited towhat has been particularly described hereinabove and other advantages ofthe present invention will be more clearly understood from the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention.

FIG. 1 is a diagram illustrating a brief structure of an evolved packetsystem (EPS) that includes an evolved packet core (EPC).

FIG. 2 is an exemplary diagram illustrating an architecture of a generalE-UTRAN and a general EPC.

FIG. 3 is an exemplary diagram illustrating a structure of a radiointerface protocol on a control plane.

FIG. 4 is an exemplary diagram illustrating a structure of a radiointerface protocol on a user plane.

FIG. 5 is a flow chart illustrating a random access procedure.

FIG. 6 is a diagram illustrating a connection procedure in a radioresource control (RRC) layer.

FIG. 7 is a diagram illustrating a 5G system.

FIG. 8 illustrates a Non-Roaming NextGe Architecture.

FIGS. 9 to 21 are diagrams illustrating examples of a detailed procedureaccording to the embodiments of the present invention.

FIG. 22 is a diagram illustrating a configuration of a node deviceaccording to the embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The embodiments below are combinations of components and features of thepresent invention in a prescribed form. Each component or feature may beconsidered as selective unless explicitly mentioned as otherwise. Eachcomponent or feature may be executed in a form that is not combined withother components and features. Further, some components and/or featuresmay be combined to configure an embodiment of the present invention. Theorder of operations described in the embodiments of the presentinvention may be changed. Some components or features of an embodimentmay be included in another embodiment or may be substituted with acorresponding component or feature of the present invention.

Specific terms used in the description below are provided to help anunderstanding of the present invention, and the use of such specificterms may be changed to another form within the scope of the technicalconcept of the present invention.

In some cases, in order to avoid obscurity of the concept of the presentinvention, a known structure and apparatus may be omitted, or a blockdiagram centering on core functions of each structure or apparatus maybe used. Moreover, the same reference numerals are used for the samecomponents throughout the present specification.

The embodiments of the present invention may be supported by standarddocuments disclosed with respect to at least one of IEEE (Institute ofElectrical and Electronics Engineers) 802 group system, 3GPP system,3GPP LTE & LTE-A system and 3GPP2 system. Namely, the steps or portionshaving not been described in order to clarify the technical concept ofthe present invention in the embodiments of the present invention may besupported by the above documents. Furthermore, all terms disclosed inthe present document may be described according to the above standarddocuments.

The technology below may be used for various wireless communicationsystems. For clarity, the description below centers on 3GPP LTE and 3GPPLTE-A, by which the technical idea of the present invention isnon-limited.

Terms used in the present document are defined as follows.

UMTS (Universal Mobile Telecommunications System): a GSM (Global Systemfor Mobile Communication) based third generation mobile communicationtechnology developed by the 3GPP.

EPS (Evolved Packet System): a network system that includes an EPC(Evolved Packet Core) which is an IP (Internet Protocol) based packetswitched core network and an access network such as LTE and UTRAN. Thissystem is the network of an evolved version of the UMTS.

NodeB: a base station of GERAN/UTRAN. This base station is installedoutdoor and its coverage has a scale of a macro cell.

eNodeB: a base station of LTE. This base station is installed outdoorand its coverage has a scale of a macro cell.

UE (User Equipment): the UE may be referred to as terminal, ME (MobileEquipment), MS (Mobile Station), etc. Also, the UE may be a portabledevice such as a notebook computer, a cellular phone, a PDA (PersonalDigital Assistant), a smart phone, and a multimedia device.Alternatively, the UE may be a non-portable device such as a PC(Personal Computer) and a vehicle mounted device. The term “UE”, as usedin relation to MTC, can refer to an MTC device.

HNB (Home NodeB): a base station of UMTS network. This base station isinstalled indoor and its coverage has a scale of a micro cell.

HeNB (Home eNodeB): a base station of an EPS network. This base stationis installed indoor and its coverage has a scale of a micro cell.

MME (Mobility Management Entity): a network node of an EPS network,which performs mobility management (MM) and session management (SM).

PDN-GW (Packet Data Network-Gateway)/PGW: a network node of an EPSnetwork, which performs UE IP address allocation, packet screening andfiltering, charging data collection, etc.

SGW (Serving Gateway): a network node of an EPS network, which performsmobility anchor, packet routing, idle-mode packet buffering, andtriggering of an MME's UE paging.

NAS (Non-Access Stratum): an upper stratum of a control plane between aUE and an MME. This is a functional layer for transmitting and receivinga signaling and traffic message between a UE and a core network in anLTE/UMTS protocol stack, and supports mobility of a UE, and supports asession management procedure of establishing and maintaining IPconnection between a UE and a PDN GW.

PDN (Packet Data Network): a network in which a server supporting aspecific service (e.g., a Multimedia Messaging Service (MIMS) server, aWireless Application Protocol (WAP) server, etc.) is located.

PDN connection: a logical connection between a UE and a PDN, representedas one IP address (one IPv4 address and/or one IPv6 prefix).

RAN (Radio Access Network): a unit including a Node B, an eNode B, and aRadio Network Controller (RNC) for controlling the Node B and the eNodeB in a 3GPP network, which is present between UEs and provides aconnection to a core network.

HLR (Home Location Register)/HSS (Home Subscriber Server): a databasehaving subscriber information in a 3GPP network. The HSS can performfunctions such as configuration storage, identity management, and userstate storage.

PLMN (Public Land Mobile Network): a network configured for the purposeof providing mobile communication services to individuals. This networkcan be configured per operator.

Proximity Services (or ProSe Service or Proximity-based Service): aservice that enables discovery between physically proximate devices, andmutual direct communication/communication through a basestation/communication through the third party. At this time, user planedata are exchanged through a direct data path without through a 3GPPcore network (for example, EPC).

EPC (Evolved Packet Core)

FIG. 1 is a schematic diagram showing the structure of an evolved packetsystem (EPS) including an evolved packet core (EPC).

The EPC is a core element of system architecture evolution (SAE) forimproving performance of 3GPP technology. SAE corresponds to a researchproject for determining a network structure supporting mobility betweenvarious types of networks. For example, SAE aims to provide an optimizedpacket-based system for supporting various radio access technologies andproviding an enhanced data transmission capability.

Specifically, the EPC is a core network of an IP mobile communicationsystem for 3GPP LTE and can support real-time and non-real-timepacket-based services. In conventional mobile communication systems(i.e. second-generation or third-generation mobile communicationsystems), functions of a core network are implemented through acircuit-switched (CS) sub-domain for voice and a packet-switched (PS)sub-domain for data. However, in a 3GPP LTE system which is evolved fromthe third generation communication system, CS and PS sub-domains areunified into one IP domain. That is, In 3GPP LTE, connection ofterminals having IP capability can be established through an IP-basedbusiness station (e.g., an eNodeB (evolved Node B)), EPC, and anapplication domain (e.g., IMS). That is, the EPC is an essentialstructure for end-to-end IP services.

The EPC may include various components. FIG. 1 shows some of thecomponents, namely, a serving gateway (SGW), a packet data networkgateway (PDN GW), a mobility management entity (MME), a serving GPRS(general packet radio service) supporting node (SGSN) and an enhancedpacket data gateway (ePDG).

The SGW operates as a boundary point between a radio access network(RAN) and a core network and maintains a data path between an eNodeB andthe PDN GW. When. When a terminal moves over an area served by aneNodeB, the SGW functions as a local mobility anchor point. That is,packets. That is, packets may be routed through the SGW for mobility inan evolved UMTS terrestrial radio access network (E-UTRAN) defined after3GPP release-8. In addition, the SGW may serve as an anchor point formobility of another 3GPP network (a RAN defined before 3GPP release-8,e.g., UTRAN or GERAN (global system for mobile communication(GSM)/enhanced data rates for global evolution (EDGE) radio accessnetwork).

The PDN GW corresponds to a termination point of a data interface for apacket data network. The PDN GW may support policy enforcement features,packet filtering and charging support. In addition, the PDN GW may serveas an anchor point for mobility management with a 3GPP network and anon-3GPP network (e.g., an unreliable network such as an interworkingwireless local area network (I-WLAN) and a reliable network such as acode division multiple access (CDMA) or WiMax network).

Although the SGW and the PDN GW are configured as separate gateways inthe example of the network structure of FIG. 1, the two gateways may beimplemented according to a single gateway configuration option.

The MME performs signaling and control functions for supporting accessof a UE for network connection, network resource allocation, tracking,paging, roaming and handover. The MME controls control plane functionsassociated with subscriber and session management. The MME managesnumerous eNodeBs and signaling for selection of a conventional gatewayfor handover to other 2G/3G networks. In addition, the MME performssecurity procedures, terminal-to-network session handling, idle terminallocation management, etc.

The SGSN handles all packet data such as mobility management andauthentication of a user for other 3GPP networks (e.g., a GPRS network).

The ePDG serves as a security node for a non-3GPP network (e.g., anI-WLAN, a Wi-Fi hotspot, etc.).

As described above with reference to FIG. 1, a terminal having IPcapabilities may access an IP service network (e.g., an IMS) provided byan operator via various elements in the EPC not only based on 3GPPaccess but also based on non-3GPP access.

Additionally, FIG. 1 shows various reference points (e.g. S1-U, S1-MME,etc.). In 3GPP, a conceptual link connecting two functions of differentfunctional entities of an E-UTRAN and an EPC is defined as a referencepoint. Table 1 is a list of the reference points shown in FIG. 1.Various reference points may be present in addition to the referencepoints in Table 1 according to network structures.

TABLE 1 Reference point Description S1-MME Reference point for thecontrol plane protocol between E-UTRAN and MME S1-U Reference pointbetween E-UTRAN and Serving GW for the per bearer user plane tunnelingand inter eNodeB path switching during handover S3 It enables user andbearer information exchange for inter 3GPP access network mobility inidle and/or active state. This reference point can be used intra-PLMN orinter- PLMN (e.g. in the case of Inter-PLMN HO). S4 It provides relatedcontrol and mobility support between GPRS Core and the 3GPP Anchorfunction of Serving GW. In addition, if Direct Tunnel is notestablished, it provides the user plane tunneling. S5 It provides userplane tunneling and tunnel management between Serving GW and PDN GW. Itis used for Serving GW relocation due to UE mobility and if the ServingGW needs to connect to a non-collocated PDN GW for the required PDNconnectivity. S11 Reference point between an MME and an SGW SGi It isthe reference point between the PDN GW and the packet data network.Packet data network may be an operator external public or private packetdata network or an intra operator packet data network, e.g. forprovision of IMS services. This reference point corresponds to Gi for3GPP accesses.

Among the reference points shown in FIG. 1, S2a and S2b correspond tonon-3GPP interfaces. S2a is a reference point which provides reliablenon-3GPP access and related control and mobility support between PDN GWsto a user plane. S2b is a reference point which provides related controland mobility support between the ePDG and the PDN GW to the user plane.

FIG. 2 is a diagram exemplarily illustrating architectures of a typicalE-UTRAN and EPC.

As shown in the figure, while radio resource control (RRC) connection isactivated, an eNodeB may perform routing to a gateway, schedulingtransmission of a paging message, scheduling and transmission of abroadcast channel (BCH), dynamic allocation of resources to a UE onuplink and downlink, configuration and provision of eNodeB measurement,radio bearer control, radio admission control, and connection mobilitycontrol. In the EPC, paging generation, LTE IDLE state management,ciphering of the user plane, SAE bearer control, and ciphering andintegrity protection of NAS signaling.

FIG. 3 is a diagram exemplarily illustrating the structure of a radiointerface protocol in a control plane between a UE and a base station,and FIG. 4 is a diagram exemplarily illustrating the structure of aradio interface protocol in a user plane between the UE and the basestation.

The radio interface protocol is based on the 3GPP wireless accessnetwork standard. The radio interface protocol horizontally includes aphysical layer, a data link layer, and a networking layer. The radiointerface protocol is divided into a user plane for transmission of datainformation and a control plane for delivering control signaling whichare arranged vertically.

The protocol layers may be classified into a first layer (L1), a secondlayer (L2), and a third layer (L3) based on the three sublayers of theopen system interconnection (OSI) model that is well known in thecommunication system.

Hereinafter, description will be given of a radio protocol in thecontrol plane shown in FIG. 3 and a radio protocol in the user planeshown in FIG. 4.

The physical layer, which is the first layer, provides an informationtransfer service using a physical channel. The physical channel layer isconnected to a medium access control (MAC) layer, which is a higherlayer of the physical layer, through a transport channel. Data istransferred between the physical layer and the MAC layer through thetransport channel. Transfer of data between different physical layers,i.e., a physical layer of a transmitter and a physical layer of areceiver is performed through the physical channel.

The physical channel consists of a plurality of subframes in the timedomain and a plurality of subcarriers in the frequency domain. Onesubframe consists of a plurality of symbols in the time domain and aplurality of subcarriers. One subframe consists of a plurality ofresource blocks. One resource block consists of a plurality of symbolsand a plurality of subcarriers. A Transmission Time Interval (TTI), aunit time for data transmission, is 1 ms, which corresponds to onesubframe.

According to 3GPP LTE, the physical channels present in the physicallayers of the transmitter and the receiver may be divided into datachannels corresponding to Physical Downlink Shared Channel (PDSCH) andPhysical Uplink Shared Channel (PUSCH) and control channelscorresponding to Physical Downlink Control Channel (PDCCH), PhysicalControl Format Indicator Channel (PCFICH), Physical Hybrid-ARQ IndicatorChannel (PHICH) and Physical Uplink Control Channel (PUCCH).

The second layer includes various layers.

First, the MAC layer in the second layer serves to map various logicalchannels to various transport channels and also serves to map variouslogical channels to one transport channel. The MAC layer is connectedwith an RLC layer, which is a higher layer, through a logical channel.The logical channel is broadly divided into a control channel fortransmission of information of the control plane and a traffic channelfor transmission of information of the user plane according to the typesof transmitted information.

The radio link control (RLC) layer in the second layer serves to segmentand concatenate data received from a higher layer to adjust the size ofdata such that the size is suitable for a lower layer to transmit thedata in a radio interval.

The Packet Data Convergence Protocol (PDCP) layer in the second layerperforms a header compression function of reducing the size of an IPpacket header which has a relatively large size and contains unnecessarycontrol information, in order to efficiently transmit an IP packet suchas an IPv4 or IPv6 packet in a radio interval having a narrow bandwidth.In addition, in LTE, the PDCP layer also performs a security function,which consists of ciphering for preventing a third party from monitoringdata and integrity protection for preventing data manipulation by athird party.

The Radio Resource Control (RRC) layer, which is located at theuppermost part of the third layer, is defined only in the control plane,and serves to configure radio bearers (RBs) and control a logicalchannel, a transport channel, and a physical channel in relation toreconfiguration and release operations. The RB represents a serviceprovided by the second layer to ensure data transfer between a UE andthe E-UTRAN.

If an RRC connection is established between the RRC layer of the UE andthe RRC layer of a wireless network, the UE is in the RRC Connectedmode. Otherwise, the UE is in the RRC Idle mode.

Hereinafter, description will be given of the RRC state of the UE and anRRC connection method. The RRC state refers to a state in which the RRCof the UE is or is not logically connected with the RRC of the E-UTRAN.The RRC state of the UE having logical connection with the RRC of theE-UTRAN is referred to as an RRC_CONNECTED state. The RRC state of theUE which does not have logical connection with the RRC of the E-UTRAN isreferred to as an RRC_IDLE state. A UE in the RRC_CONNECTED state hasRRC connection, and thus the E-UTRAN may recognize presence of the UE ina cell unit. Accordingly, the UE may be efficiently controlled. On theother hand, the E-UTRAN cannot recognize presence of a UE which is inthe RRC_IDLE state. The UE in the RRC_IDLE state is managed by a corenetwork in a tracking area (TA) which is an area unit larger than thecell. That is, for the UE in the RRC_IDLE state, only presence orabsence of the UE is recognized in an area unit larger than the cell. Inorder for the UE in the RRC_IDLE state to be provided with a usualmobile communication service such as a voice service and a data service,the UE should transition to the RRC_CONNECTED state. A TA isdistinguished from another TA by a tracking area identity (TAI) thereof.A UE may configure the TAI through a tracking area code (TAC), which isinformation broadcast from a cell.

When the user initially turns on the UE, the UE searches for a propercell first. Then, the UE establishes RRC connection in the cell andregisters information thereabout in the core network. Thereafter, the UEstays in the RRC_IDLE state. When necessary, the UE staying in theRRC_IDLE state selects a cell (again) and checks system information orpaging information. This operation is called camping on a cell. Onlywhen the UE staying in the RRC_IDLE state needs to establish RRCconnection, does the UE establish RRC connection with the RRC layer ofthe E-UTRAN through the RRC connection procedure and transition to theRRC_CONNECTED state. The UE staying in the RRC_IDLE state needs toestablish RRC connection in many cases. For example, the cases mayinclude an attempt of a user to make a phone call, an attempt totransmit data, or transmission of a response message after reception ofa paging message from the E-UTRAN.

The non-access stratum (NAS) layer positioned over the RRC layerperforms functions such as session management and mobility management.

Hereinafter, the NAS layer shown in FIG. 3 will be described in detail.

The eSM (evolved Session Management) belonging to the NAS layer performsfunctions such as default bearer management and dedicated bearermanagement to control a UE to use a PS service from a network. The UE isassigned a default bearer resource by a specific packet data network(PDN) when the UE initially accesses the PDN. In this case, the networkallocates an available IP to the UE to allow the UE to use a dataservice. The network also allocates QoS of a default bearer to the UE.LTE supports two kinds of bearers. One bearer is a bearer havingcharacteristics of guaranteed bit rate (GBR) QoS for guaranteeing aspecific bandwidth for transmission and reception of data, and the otherbearer is a non-GBR bearer which has characteristics of best effort QoSwithout guaranteeing a bandwidth. The default bearer is assigned to anon-GBR bearer. The dedicated bearer may be assigned a bearer having QoScharacteristics of GBR or non-GBR.

A bearer allocated to the UE by the network is referred to as an evolvedpacket service (EPS) bearer. When the EPS bearer is allocated to the UE,the network assigns one ID. This ID is called an EPS bearer ID. One EPSbearer has QoS characteristics of a maximum bit rate (MBR) and/or aguaranteed bit rate (GBR).

FIG. 5 is a flowchart illustrating a random access procedure in 3GPPLTE.

The random access procedure is used for a UE to obtain ULsynchronization with an eNB or to be assigned a UL radio resource.

The UE receives a root index and a physical random access channel(PRACH) configuration index from an eNodeB. Each cell has 64 candidaterandom access preambles defined by a Zadoff-Chu (ZC) sequence. The rootindex is a logical index used for the UE to generate 64 candidate randomaccess preambles.

Transmission of a random access preamble is limited to a specific timeand frequency resources for each cell. The PRACH configuration indexindicates a specific subframe and preamble format in which transmissionof the random access preamble is possible.

The UE transmits a randomly selected random access preamble to theeNodeB. The UE selects a random access preamble from among 64 candidaterandom access preambles and the UE selects a subframe corresponding tothe PRACH configuration index. The UE transmits the selected randomaccess preamble in the selected subframe.

Upon receiving the random access preamble, the eNodeB sends a randomaccess response (RAR) to the UE. The RAR is detected in two steps.First, the UE detects a PDCCH masked with a random access (RA)-RNTI. TheUE receives an RAR in a MAC (medium access control) PDU (protocol dataunit) on a PDSCH indicated by the detected PDCCH.

FIG. 6 illustrates a connection procedure in a radio resource control(RRC) layer.

As shown in FIG. 6, the RRC state is set according to whether or not RRCconnection is established. An RRC state indicates whether or not anentity of the RRC layer of a UE has logical connection with an entity ofthe RRC layer of an eNodeB. An RRC state in which the entity of the RRClayer of the UE is logically connected with the entity of the RRC layerof the eNodeB is called an RRC connected state. An RRC state in whichthe entity of the RRC layer of the UE is not logically connected withthe entity of the RRC layer of the eNodeB is called an RRC idle state.

A UE in the Connected state has RRC connection, and thus the E-UTRAN mayrecognize presence of the UE in a cell unit. Accordingly, the UE may beefficiently controlled. On the other hand, the E-UTRAN cannot recognizepresence of a UE which is in the idle state. The UE in the idle state ismanaged by the core network in a tracking area unit which is an areaunit larger than the cell. The tracking area is a unit of a set ofcells. That is, for the UE which is in the idle state, only presence orabsence of the UE is recognized in a larger area unit. In order for theUE in the idle state to be provided with a usual mobile communicationservice such as a voice service and a data service, the UE shouldtransition to the connected state.

When the user initially turns on the UE, the UE searches for a propercell first, and then stays in the idle state. Only when the UE stayingin the idle state needs to establish RRC connection, the UE establishesRRC connection with the RRC layer of the eNodeB through the RRCconnection procedure and then performs transition to the RRC connectedstate.

The UE staying in the idle state needs to establish RRC connection inmany cases. For example, the cases may include an attempt of a user tomake a phone call, an attempt to transmit data, or transmission of aresponse message after reception of a paging message from the E-UTRAN.

In order for the UE in the idle state to establish RRC connection withthe eNodeB, the RRC connection procedure needs to be performed asdescribed above. The RRC connection procedure is broadly divided intotransmission of an RRC connection request message from the UE to theeNodeB, transmission of an RRC connection setup message from the eNodeBto the UE, and transmission of an RRC connection setup complete messagefrom the UE to eNodeB, which are described in detail below withreference to FIG. 6.

1) When the UE in the idle state desires to establish RRC connection forreasons such as an attempt to make a call, a data transmission attempt,or a response of the eNodeB to paging, the UE transmits an RRCconnection request message to the eNodeB first.

2) Upon receiving the RRC connection request message from the UE, theENB accepts the RRC connection request of the UE when the radioresources are sufficient, and then transmits an RRC connection setupmessage, which is a response message, to the UE.

3) Upon receiving the RRC connection setup message, the UE transmits anRRC connection setup complete message to the eNodeB. Only when the UEsuccessfully transmits the RRC connection setup message, does the UEestablish RRC connection with the eNode B and transition to the RRCconnected mode.

In the legacy EPC, MME is categorized into AMF(Core Access and MobilityManagement Function) and SMF(session Management Function) in a NextGeneration system (or 5G core network (CN)). Therefore, NAS interactionand MM (Mobility Management) with the UE are performed by the AMF, andSM (Session Management) is performed by the SMF. Also, the SMF manages aUPF (User plane Function) which is a gateway having a user-planefunction, that is, for routing user traffic. In this case, acontrol-plane portion of S-GW and P-GW in the legacy EPC may be managedby the SMF, and a user-plane portion may be managed by the UPF. Forrouting of user traffic, one or more UPFs may exist between RAN and DN(Data Network). That is, the legacy EPC may be configured in 5G asillustrated in FIG. 7. Also, as a concept corresponding to PDNconnection in the legacy EPS, a PDU (Protocol Data Unit) session isdefined in the 5G system. The PDU session refers to association betweena UE, which provides PDU connectivity services of Ethernet type orunstructured type as well as IP type, and a DN. In addition, a UDM(Unified Data Management) performs a function corresponding to HSS ofEPC, and PCF (Policy Control Function) performs a function correspondingto PCRF of the EPC. To satisfy requirements of the 5G system, thefunctions may be provided in an enlarged type. N1 is a reference pointfor a control plane between 5G UE and AMF, N2 is a reference point for acontrol plane between 5G (R)AN and AMF, and N3 is a reference point fora user plane between 5G (R)AN and UPF. Also, N4 is a reference pointbetween SMF and UPF, N5 is a reference point between PCF and applicationfunction, and N6 is a reference point between UPF and a data network.The data network may be a public or private data network outside amobile communication provider, or may be a mobile communication providerdata network. N7 is a reference point between SMF and PCF. Details ofthe 5G system architecture, each function and each interface follows TS23.501. Particularly, the 5G system (that is, next generation system)should support non-3GPP access, and thus details such as architecturefor supporting non-3GPP access and network element are described inclause 4.2.7 of TS 23.501v0.2.0. A main example of non-3GPP access mayinclude WLAN access that may include a trusted WLAN and an untrustedWLAN.

An architecture which includes various types of non-3GPP accesses issuggested in TS 23.501. For example, AMF (that is, serving AMF for 3GPPaccess of UE) for 3GPP access may be different from AMF (that is,serving AMF for non-3GPP access of UE) for non-3GPP access as shown inFIG. 8. This is because that PLMNs to/in which the respective accessesbelong/are located are different from each other.

If the number of serving AMFs for the UE is 2, UDM which should storethe serving AMFs cannot identify an access type of the correspondingserving AMF in case of a serving node registration request (for example,(Nudm_Serving NF_Registration service) operation in clause 5.2.3.1 of TS23.502v0.3.0) from the AMF. Therefore, if the serving AMF for the UEalready exists, the UDM cannot determine whether to replace the servingAMF or add serving AFM for another access. In addition, when a randomnetwork entity queries information on the serving AMF of the UE for theUDM or requests the UDM of operation to the serving AMF, a problemoccurs in that the UDM cannot determine an access type of the AMF.

Hereinafter, a method for efficiently managing a serving AMF or a methodfor managing information on the serving AMF in a state that AMF mayexist per access in respect of 3GPP and non-3GPP access will bedescribed.

Embodiment

The UDM according to one embodiment of the present invention may receivea message related to serving AMF registration of the UE from a first AMFin a procedure related to a registration of AMF (Access and MobilityManagement Function), wherein the message includes access typeinformation and ID (identity) information. The UDM stores the accesstype information on the AMF and the ID information. If a second AMFregistered as a serving AMF of the UE, which corresponds to the accesstype information, exists, the UDM may transmit a deregistration relatedmessage to a second AMF. The access type may include 3GPP access andnon-3GPP access. (The access type information related to the AMF and theID information may be stored for both of the case that the second AMFregistered as the serving AMF of the UE, which corresponds to the accesstype information, exists and the case that the second AMF does notexist.)

That is, the message transmitted to register the AMF as the serving AMFincludes ID of the AMF, and notifies the UDM of information indicatingan access type of the AMF. The UDM stores ID of the AMF together withaccess type information associated with AMF ID unlike the related art inwhich the UDM stores only ID of the AMF. In this case, the UDM maymanage the AMF per access type, and if the AMF registered as the servingAMF of the UE, which is the same as the received access type, alreadyexists, the UDM deregisters the AMF which is previously registered. AMFID included in the message transmitted from the AMF may be one or moreof AMF address, AMF NF (Network Function) ID, AMF identifier, AMF IPaddress, and FQDN of AMF, and may include NF type information.Alternatively, AMF ID may be GUAMI (Globally Unique AMF Identifier)type. This may be applied to AMF ID included in a message transmittedfrom another NF as well as a message transmitted from the AMF. Also,this may be applied to NF ID included in the message transmitted fromthe NF. ID of AMF, which is stored by the UDM, may be AMF ID included inthe message transmitted from the AMF, or information of a part of theAMF ID, or may be ID modified in the form understood by the UDM. Thismay also be applied to ID of NF, which is stored by the UDM, on thewhole of the present invention.

The aforementioned operation will be described in detail through ageneral registration procedure with reference to FIG. 9. A generalregistration procedure of 3GPP TS 23.502v0.3.0 is shown in FIG. 9. InFIG. 9, step S901, which is related to transmission of a registrationrequest of the UE, to step S913 and details of steps S915 to S923 willbe replaced with the description of general registration of 3GPP TS23.502v0.3.0.

In step S914, if the AMF is changed due to the last registrationprocedure, if there is no valid subscription context for the UE in theAMF, or if the UE provides SUPI(Subscription Permanent Identifier) whichdoes not refer to valid context in the AMF, a new AMF starts UpdateLocation procedure. The new AMF provides the UDM with an access typewhich is served. If AMF related to the access type exists, it includesthat the UDM initiates cancel location to this AMF, that is, old AMF.The UDM stores the access type related to the serving AMF (information)together with the serving AMF(information). (Details of the operationthat the new AMF provides the UDM with access type information andrelated UDM operation will be understood with reference to thedescription made in FIG. 11.) The old AMF notifies deletes MM contextand notifies all possible and associated SMFs of the deleted MM context,and the new AMF generates MM context for the UE after obtaining AMFrelated subscription data from the UDM. At this time, the old AMF maydelete MM context related to a 3GPP access and report the deleted MMcontext to SMF(s) for PDU session on a 3GPP access. The new AMF maygenerate MM context for 3GPP access. The old AMF and the new AMFrecognize that access type is a 3GPP access. This is because that accessacquired from the UDM or served by the UDM is only a 3GPP access.

In this procedure, if the UE is registered in the same AMF alreadyregistered in a non-3GPP access, (for example, UE is registered over anon-3GPP access and initiates this registration procedure to add a 3GPPaccess), the UE should transmit AMF Notify Request (AMF ID, access type)message to the UDM. The access type is set to “3GPP access”, and NotifyRequest is to register a serving AMF for a 3GPP access in the UDM. TheUDM transmits a Notify Response message to the AMF. As described above,although the AMF may notify the UDM addition of a new access through theNotify Request message, various messages such as Location Update Requestmessage may be used.

A registration procedure through an untrusted non-3GPP access is shownin FIG. 10. After step S1007, the steps S913 and S914 of FIG. 9 areperformed. Although the description of FIG. 9 is based on that theaccess type is a 3GPP access, this description will be given based onthat the access type is a non-3GPP access. The steps S913 and S914 maybe performed prior to the step S1007. In addition, detailed descriptionof each procedure in FIG. 10 will be replaced with the description ofRegistration via Untrusted non-3GPP Access of 3GPP TS 23.502v0.3.0.

A Service/service operation information flow of Nudm_ServingNF_Registration service is shown in FIG. 11. In this case, theNudm_Serving NF_Registration service may be specified as listed in Table2 below. In the following description, the scope of the presentinvention is not limited to a specific name.

TABLE 2 Service or service operation name: Nudm_Serving NF_RegistrationDescription: Register UE's serving NF on the UDM Known NF Consumers:AMF, SMF, SMSF Concurrent use: No. Pre-requisite conditions: No Postconditions: UDM stores the Requester NF ID in the UE context. Inputs,Required: Requester NF ID, SUPI. Inputs, Optional: subscription dataretrieval indication. Outputs, Required: Result indication. Outputs,Optional: UE subscription data is retrieved by the Requester NF ID, ifthe subscription data retrieval indication is included.

Referring to FIG. 11, in step S1101, a Requester NF desires to beregistered in the UDM as a serving NF of the UE. The Requester NFtransmits a Register UE serving NF Request (SUPI, NF ID) message to theUDM. NF ID indicates NF type and ID of the serving NF. Selectively, inaccordance with NF type of the Requester, the request message mayinclude additional information stored in the UDM. For example, if the NFis SMF, the NF type may include related APN.

If the type of the Requester is AMF, the Request message includes accesstype (for example, “3GPP access” or “Non-3GPP access”) stored togetherwith AMF (information) in the UDM.

The AMF may perform the step S1101 per access type. For example, if UE#1 is registered in AMF #1 through the 3GPP access, the AMF #1 transmitsthe Request message, which includes access type=“3GPP access”, to theUDM. Afterwards, if the UE #1 is registered in the AMF #1 through thenon-3GPP access, the AMF #1 transmits the Request message, whichincludes access type=“Non-3GPP access”, to the UDM. For another example,if UE #2 is registered in AMF #2 through the 3GPP access, the AMF #2transmits the Request message, which includes access type=“3GPP access”,to the UDM. Afterwards, if the UE #2 is registered in AMF #3 through thenon-3GPP access, the AMF #3 transmits the Request message, whichincludes access type=“Non-3GPP access”, to the UDM.

Although the above description is given based on that the access typeinformation is “3GPP access” or “Non-3GPP access”, the access typeinformation may be expressed in the form of various levels/formats. Forexample, the 3GPP access may be expressed as NG-RAN (or NR) or E-UTRAN(or LTE). Also, the 3GPP access may be expressed as its detailed RAN.The non-3GPP access may be expressed as an untrusted non-3GPP access, atrusted non-3GPP access, WLAN, etc. Also, the non-3GPP access may beexpressed as its detailed access. Also, the access type may indicate allaccess types such as “All accesses” or “Both accesses”. In this way, ifthe access type indicates all access types and the step S1101 isperformed, the AMF may delay the step S1101 until the AMF recognizesthat the AMF is a serving AMF for all access types. Also, the accesstype information may be indicated implicitly. For example, RAT type maybe inferred through location information (Cell ID, SSID of WLAN AP,etc.) of the UE. Also, the access type information may be construed asRAT type information. Description and operation related to the accesstype may be applied to the present invention as they are, or may beapplied thereto by modification.

The AMF may include access type information in the Request message forall UEs (that is, always). Alternatively, the AMF may include accesstype information in the Request message if one or more of the followingconditions are fulfilled. This is applied to the present invention.

i) The case that the UE may receive a service through non-3GPP access(or WLAN).

ii) The case that the UE may perform handover to non-3GPP access (orWLAN).

iii) The case that PLMN in/to which AMF is located/belongs does notsupport non-3GPP access (or WLAN).

iv) The case that PLMN in/to which AMF is located/belongs does notsupport/include N3IWF.

The case that the access type served by the AMF is the 3GPP access maynot include the access type information. In this case, the UDM mayregard that associated access of the AMF is the 3GPP access. Also, inthis case, since the access type indicates that the access type is onlythe non-3GPP access, flag (or bit) is given to 1 or Yes or Set, wherebyit may indicate that the AMF serves the non-3GPP access. If the accesstype information includes flag, it may indicate that the AMF serves thenon-3GPP access. (For example, flag name is given to N3GPP Flag). Thisis applied to the present invention.

Optionally if the access type information includes subscription dataretrieval indication, the Requester NF requests the UDM to return UEsubscription data related to the NF type from the response message. Thisindication is reported implicitly by (UDM_SubscriptionData_UpdateNotification, see FIG. 18) when data is not changed orsynchronized any more.

When the Requester NF transmits a Register UE serving NF Request messageto the UDM, it implicitly notifies change (for example, “Nudm_ServingNF_ChangeNotification” and “Nudm_Subscription Data_UpdateNotification”services) of NF ID. Subscription to this notification service may besubscription to the corresponding access type.

In step S1102, the UDM stores a registered serving NF in UE context. NFtype related to subscription data returns to the Requester NF ifsubscription data retrieval indication is included in the requestmessage.

If the registered serving NF is the AMF, the UDM stores the associatedaccess type together with the serving NF. If the AMF related to theassociated access type exists in the UDM with respect to the UE, the UDMreplaces the existing AMF with the new AMF, that is, Requester NF. Inthis case, the UDM may additionally transmit a cancel location messageto the existing AMF. Finally, if the AMF for the associated access typedoes not exist in the UDM, the UDM stores new AMF information (theRequester NF with the access type).

Meanwhile, if the UDM receives a request message related to deletion ofUE context from the NF and the NF is AMF, the request message related todeletion of the UE context may include access type information. In thisregard, a Service/service operation information flow of Nudm_SubscriberData_Purge service is shown in FIG. 12(a).

In step S1201, the Requester NF transmits a Purge UE data request (SUPI)message to the UDM. This is a request for allowing the UDM to delete thestored Requester NF from the UE context. When the Requester NF transmitsthe Purge UE data request message, an associated access type of the NFmay be included in this message. The associated access type may beincluded in the message only when the NF is the AMF. Also, the accesstype information may be included in the message only in case of thenon-3GPP access.

In step S1202, the UDM removes the Requester NF from the UE context andresponds to the requester NF as a Purge UE response. Afterwards, the UDMdoes not transmit subscription data update notifications to therequester any more. The UDM deletes the Requester NF from the UE contextwith respect to access type related to the access type information, thatis, requested access type (or access type regarded to be requested) onthe basis of the access type information included or not included in therequest message. At this time, the access type information may beincluded in the response.

In the aforementioned description, Nudm_Subscriber Data_Purge may bespecified as listed in Table 3 below.

TABLE 3 Service or service operation name: Nudm_Subscriber Data_PurgeDescription: UDM deletes the information related to the Requester NF inthe UE context. Known NF Consumers: AMF, SMF, SMSF Concurrent use: No.Pre-requisite conditions: None Post conditions: UDM deletes theinformation related to the Requester NF in the UE context. Inputs,Required: SUPI Inputs, Optional: None Outputs, Required: ResultIndication. Outputs, Optional: None

Meanwhile, whenever a user profile is changed in the UDM, and wheneverthe change affects a user profile of the AMF, the UDM notifies the AMFaffected by the change of the changes through a “Subscriber Data UpdateNotification to AMF” procedure. In this case, the AMF adds or changesthe user profile. When the UDM performs the Subscriber Data UpdateNotification to AMF operation for the AMF, information indicating anaccess type of a user profile change may be provided to the AMF. If AMFwhich serves 3GPP access is different from AMF which serves non-3GPPaccess, the UDM performs the Subscriber Data Update Notification to AMFoperation for the AMF which is serving access related to the userprofile change. The “Subscriber Data Update Notification” service isused to allow the UDM to update subscriber data stored in the AMF.

The AMF initiates a proper operation in accordance with the changedsubscriber data. For example, if the updated subscription data indicatesthat the UE is not allowed for roaming within a network, the AMFinitiates an AMF initiated De-registration procedure. If the AMF isserving one access even there is no information, the AMF performs aproper operation related to the changed subscriber information withrespect to the access on the basis of the information on the access typeprovided from the UDM.

A Purge of subscriber data from AMF procedure is shown in FIG. 12(b). Instep 51211, after MM context and subscriber data of a de-registered UEare removed, the AMF transmits a Purge UE (SUPI) message to the UDM.When the AMF transmits the Purge UE message to the UDM, an access typeof the purge UE message may be included in this message explicitly orimplicitly. If the access type of the purge UE message is included inthe message explicitly, the access type may be included in the messagein the form of 3GPP access, non-3GPP access, and information indicatingtwo accesses. If the access type of the purge UE message is included inthe message implicitly, the access type may be notified by includinglocation information of the UE. For example, information such as cell IDmay be construed as 3GPP access, and information such as SSID of WLAN APmay be construed as non-3GPP access. If the two accesses are purged,location information on the two accesses may be included in thecorresponding information.

In step S1212, the UDM sets a UE Purged flag and responds through aPurge UE Ack message. The UDM may manage the UE Purged flag per accesstype. Therefore, the UDM sets the UE Purged flag related to the purgedaccess on the basis of information provided by the AMF, information onaccess served by the AMF, etc.

Service/service operation information flow of Nudm_ServingNF_RemoveNotification service is shown in FIG. 13. In step S1301, if theUDM detects that the UE serving NF is removed (for example, new AMF isregistered in UDM), the UDM notifies the Requester NF previouslysubscribed to the Nudm_Serving NF_RemoveNotification service of thedetected result through UE Serving NF Remove Notification (SUPI, servingNF remove reason). The provided serving NF remove reason indicates whythe NF is removed (for example, update due to a new serving NF isregistered). The Requester NF may additionally perform a relatedprocess. (For example, remove the UE context it maintains when the UE isnot served by the requester). The UDM may perform the above operation tobe suitable for access type served by the AMF. That is, if the RequesterNF is subscribed to Nudm_Serving NF_RemoveNotification service for aspecific access type, and when the UE serving NF related to thecorresponding access type is removed, this may be notified to theRequester NF. At this time, the associated access type of the serving NFmay be added to the UE Serving NF Remove Notification message.

In the aforementioned description, Nudm_Serving NF_RemoveNotificationmay be specified as listed in Table 4 below.

TABLE 4 Service or service operation name: Nudm_ServingNF_RemoveNotification Description: UDM notifies the Requester NF, whichhas subscribed the remove notification before, the Requester NF ID hasbeen removed from the UDM due to a new serving NF for the UE registeredin the UDM. Known NF Consumers: AMF, SMF, SMSF Concurrent use: No.Pre-requisite conditions: UDM detects UE's serving NF is removed Postconditions: None. Inputs, Required: Serving NF registered in UDMimplicitly/explicitly Inputs, Optional: None. Outputs, Required: SUPI,serving NF change reason SUPI, serving NF removal reason. Outputs,Optional: None

Meanwhile, if the UDM transmits a deregistration related message due tosubscription withdrawn, the UDM may indicate an access type of thederegistration related message.

The above-described operation will be described through UDM initiatedDeregistration procedure with reference to FIG. 14. The Deregistrationprocedure of 3GPP TS 23.502v0.3.0 is shown in FIG. 14. In FIG. 14,details after step S1403 will be replaced with the description ofDeregistration procedures of 3GPP TS 23.502v0.3.0.

In step S1401 a, if the UDM desires to immediately delete MM contextsand PDU sessions of subscriber, the UDM should transmit a CancelLocation (SUPI(Subscriber Permanent Identifier), Cancellation Type)message together with a cancellation type for which SubscriptionWithdrawn is configured with respect to the registered AMF.

When the UDM transmits the Cancel Location message, the UDM may add anaccess type of a cancel request. The UDM may add the above informationonly if the AMF is serving both of 3GPP access and non-3GPP access. Ifthe AMF is serving the two accesses despite that the above informationis not included therein, the AMF may regard that i) a cancel request forall accesses served by the AMF is transmitted from the corresponding UE,ii) a cancel request for only 3GPP access is transmitted, and iii) acancel request for only non-3GPP access is transmitted. This may beregarded as i), ii) or iii) on the basis of information such as localconfiguration, operator policy, etc. included in the AMF.

If a serving AMF for 3GPP access is different from a serving AMF fornon-3GPP access, the UDM transmits the Cancel Location message to theAMF related to an access of which cancellation should be requested. Ifthe two accesses should be cancelled (this may be construed thatcancellation should be performed regardless of access), Cancel Locationmessage should be transmitted to each of two AMFs. If there isinformation indicating an access type of a cancel request, the AMF maydetermine the access type of the cancel request on the basis of theinformation. Or, even if there is no information indicating an accesstype of a cancel request, since the AMF knows an access type served byitself, the AMF may determine the access type of the cancel request.

In step S1402, if Cancellation Type is Subscription Withdrawn, AMFhaving active UE context notifies a UE which is in CM-CONNECTED state ofthe deregistered fact by transmitting Deregistration Request(Deregistration Type) message to the UE. If Cancel Location messageincludes a flag indicating that re-attach is required, the AMF shouldconfigure a Deregister Type to indicate that re-attach is required. Ifthe UE is in CM-IDLE state, the AMF pages the UE. As described above,since the AMF may recognize the access type of which cancellation isrequested or the access type determined to be cancelled, the AMFperforms a deregistration operation of the UE for the correspondingaccess. If deregistration should be performed for both of 3GPP accessand non-3GPP access, the AMF may explicitly or implicitly notify thatderegistration should be performed for two accesses while transmittingDeregistration Request to one access.

Meanwhile, if a message for requesting serving AMF information isreceived from the NF, the UDM transmits serving AMF information relatedto the access type to the NF, wherein the message for requesting theserving AMF information may include access type information.

In this regard, Service/service operation information flow ofNudm_Serving NF_Get service is shown in FIG. 15(a).

In step S1501, NF consumer transmits a Get UE Serving NF Request (UE ID,NF type) message to the UDM to get a UE serving NF. The NF typeindicates which type of NF (for example, AMF, SMF, etc.) has beenqueried. When the NF consumer (that is, Requester) transmits the Get UEServing NF Request message, the NF consumer may include associatedaccess type information of the serving NF in this message. This accesstype information may be included in the corresponding message only ifthe NF type is AMF. Also, the access type information may be included inthe corresponding message only in case of non-3GPP access.

In step S1502, the UDM verifies whether the Requester NF is allowed toaccess required subscriber serving NF data. If so, the UDM provides therequester with required subscriber serving NF (for example, FQDN oraddress of serving NF). The UDM provides serving NF of the UE withrespect to access type related to the access type information, that is,requested access type (or access type regarded to be requested) on thebasis of the access type information included or not included in therequest message. At this time, the access type information may beincluded in the response.

The UDM may unconditionally provide AMF ID related to 3GPP access to theresponse if the request message of step S1501 is received. This may beconstrued that it is assumed that details on the access type informationsuggested as above are not added.

In this case, Nudm_Serving NF_Get service may be specified as listed inTable 5 below. In the following description, the scope of the presentinvention is not limited to a specific name, etc.

TABLE 5 Service or service operation name: Nudm_Serving NF_GetDescription: The Requester NF request the UDM to get the serving NF ofthe UE. Known NF Consumers: NEF Concurrent use: No. Pre-requisiteconditions: None Post conditions: None. Inputs, Required: UE ID, NF TypeInputs, Optional: None Outputs, Required: SUPI, Serving NF ID of the NFtype requested by Requester NF. Outputs, Optional: None

Service/service operation information flow of Nudm_Subscriber Data_Getservice is shown in FIG. 15(b).

In step S1511, the Requester NF requests the UDM to correspondingsubscriber data while providing UE ID (for example, SUPI) and NF typeinformation.

In step S1512, if the NF type is SMF, DNN is also included. When theRequester NF transmits the Get Subscriber Data Request message, theRequester NF may include access type information in this message. Theaccess type information may be included in the corresponding messageonly if the NF is AMF. Also, the access type information may be includedin the corresponding message only in case of non-3GPP access.

In step S1512, the UDM checks UE ID and NF type to retrieve thecorresponding subscriber data and provide the data to the Requester NF.If the Requester NF is SMF, the subscriber data include PDU type(s),authorized SSC mode(s), Default QoS profile, etc., for example. The UDMprovides the Requester NF with subscriber information on access typerelated to the access type information, that is, requested access type(or access type regarded to be requested) on the basis of the accesstype information included or not included in the request message. Atthis time, the access type information may be included in the response.

In this case, Nudm_Subscriber Data_Get may be specified as listed inTable 6 below. In the following description, the scope of the presentinvention is not limited to a specific name, etc.

TABLE 6 Service name: Nudm_Subscriber Data_Get Description: Requester NFgets the subscriber data from UDM Known NF Consumers: SMF, SMSF, AMF,AUSF Concurrent use: No. Pre-requisite conditions: None Post conditions:None Inputs, Required: SUPI, NF type. Inputs, Optional: DNN if the NFtype is SMF. Outputs, Required: The Requester NF gets the requestedsubscription data. Outputs, Optional: None

Meanwhile, the UDM may receive a request for requesting to provide UEreachability information from the NF, wherein the request for requestingto provide the UE reachability information may include access typeinformation. The UDM may be subscribed to a notification service for UEreachability event to the AMF related to the access type. If informationindicating that the UE is reachable is received from the AMF related tothe access type, the UDM may transmit the information indicating thatthe UE is reachable, to the NF.

The above-described operation will be described in detail throughReachability procedures with reference to FIG. 16. The Reachabilityprocedures of 3GPP TS 23.502v0.3.0 is shown in FIG. 16.

In step S1600, in the registration procedure or the subscription updateprocedure, the UDM notifies the AMF of identifies (for example, FQDNs)of network entities in which notification request for reachability ofthe UE is granted. The UDM and the SMSF are basically granted.

When the UDM notifies the AMF of network entity(entities) which has(have) requested UE reachability notification, the UDM may provide anaccess type desired by each network entity to get a reachabilitynotification service. The access type may be determined based onassociated information provided from each network entity, information(local configuration, operator policy, etc.) configured in the UDM,type/property of the entity (e.g., service provided by the entity), andsubscriber information of the UE. The UDM may provide the aboveinformation only if the AMF is serving both of 3GPP access and non-3GPPaccess. If the AMF is serving the two accesses despite that the aboveinformation is not included therein, the AMF may regard that i) areachability notification request for all accesses served by the AMF istransmitted from the corresponding UE, ii) a reachability notificationrequest for only 3GPP access is transmitted, and iii) a reachabilitynotification request for only non-3GPP access is transmitted. This maybe regarded as i), ii) or iii) on the basis of local configuration,operator policy, subscriber information of the UE, etc. included in theAMF.

If a serving AMF for 3GPP access is different from a serving AMF fornon-3GPP access, the UDM transmits a message indicating the networkentity to the AMF related to an access of which UE reachabilitynotification should be requested. If there is information indicating anaccess type of a reachability notification request, the AMF maydetermine the access type of the reachability notification request onthe basis of the information. Or, even if there is no informationindicating an access type of a reachability notification request, sincethe AMF knows an access type served by itself, the AMF may determine theaccess type of the reachability notification request.

The AMF may store access type information indicating an access type ofeach entity which has requested a UE reachability notification, togetherwith entity ID.

In step S1601, if a service-related entity requests the UDM to provide aUE reachability notification, the UDM checks that the entity has beengranted to perform the request on subscriber. If the entity has not beengranted, the request is rejected (for example, if the requesting entityis recognized as being a valid entity, but not authorized for thatsubscriber) or the request is disregarded. (For example, if therequesting entity is not recognized). A proper O&M report is generated.

When the service-related entity requests the UDM of UE reachabilitynotification, an access type of a reachability notification servicedesired to be received may be added to the request. If the aboveinformation is not included in the request, the UDM may regard that i) anotification request for all accesses is transmitted from thecorresponding UE, ii) a notification request for only 3GPP access istransmitted, and iii) a notification request for only non-3GPP access istransmitted. This may be regarded as i), ii) or iii) on the basis oflocal configuration, operator policy, type/property (e.g., serviceprovided by the entity) which has requested the reachabilitynotification, subscriber information of the UE, etc. included in theUDM.

The UDM may store access type information indicating an access type ofeach entity which has requested a UE reachability notification, togetherwith entity ID.

In step S1602 a, the UDM stores identity of the service-related entityand sets URRP-AMF parameter as reception of the request. If a value ofthe URRP-AMF parameter is changed from “not set” to “set”, the UDMtransmits UE-REACHABILITY-NOTIFICATION-REQUEST (URRP-AMF) to the AMF.When the UDM requests the AMF of UE reachability notification, the UDMmay provide an access type of the reachability notification servicedesired to be received. This access type may be determined based onaccess type information received from the entity which has requested theUDM of the UE reachability notification, information (localconfiguration, operator policy, etc.) configured in the UDM,type/property (e.g., service provided by the entity) of the entity,subscriber information of the UE, etc. The UDM may provide the aboveinformation only if the AMF is serving both of 3GPP access and non-3GPPaccess. If the AMF is serving the two accesses despite that the aboveinformation is not included therein, the AMF may regard that i) areachability notification request for all accesses served by the AMF istransmitted from the corresponding UE, ii) a reachability notificationrequest for only 3GPP access is transmitted, and iii) a reachabilitynotification request for only non-3GPP access is transmitted. This maybe regarded as i), ii) or iii) on the basis of local configuration,operator policy, subscriber information of the UE, etc. included in theAMF.

If a serving AMF for 3GPP access is different from a serving AMF fornon-3GPP access, the UDM transmits the request message to the AMFrelated to an access of which UE reachability notification should berequested. If there is information indicating an access type of areachability notification request, the AMF may determine the access typeof the reachability notification request on the basis of theinformation. Or, even if there is no information indicating an accesstype of a reachability notification request, since the AMF knows anaccess type served by itself, the AMF may determine the access type ofthe reachability notification request.

The URRP-AMF parameter managed by the UDM may be managed per access. Forexample, if a random entity requests UE reachability notification withrespect to 3GPP access, the URRP-AMF parameter for 3GPP access is set to“set”.

The AMF may store access type information indicating an access type ofthe UDM which has requested a UE reachability notification, togetherwith entity ID.

In step S1602 b, the SMSF transmits UE-REACHABILITY-NOTIFICATION-REQUEST(URRP-AMF) to the AMF. When the SMSF requests the AMF of UE reachabilitynotification, the SMSF may add an access type of the reachabilitynotification service desired to be received. If the above information isnot included in the request, the AMF may regard that i) a notificationrequest for all accesses is transmitted from the corresponding UE, ii) anotification request for only 3GPP access is transmitted, and iii) anotification request for only non-3GPP access is transmitted. This maybe regarded as i), ii) or iii) on the basis of local configuration,operator policy, subscriber information of the UE, etc. included in theAMF. Alternatively, if the above information is not included in therequest, the AMF may regard that a notification request for 3GPP accessis transmitted because the SMSF is a function which is in charge of SMS.The AMF may store access type information indicating an access type ofthe SMSF which has requested a UE reachability notification, togetherwith SMSF ID.

In step S1603, the AMF checks that a requesting entity has been grantedto perform the request of the subscriber. If the entity has not beengranted, the request is rejected (for example, if the requesting entityis recognized as being a valid entity, but not authorized for thatsubscriber) or the request is disregarded. (For example, if therequesting entity is not recognized). A proper O&M report is generated.

If the AMF has MM Context for the corresponding user, the AMF configuresURRP-AMF to indicate that it is required to report UDM informationregarding changes from UE reachability. (For example, when the next NASactivity with that UE is detected.)

The URRP-AMF parameter managed by the AMF may be managed per access. Forexample, if the UDM has requested UE reachability notification withrespect to 3GPP access, the UDM sets the URRP-AMF parameter for 3GPPaccess to “set”.

Since the UDM receives UE reachability notification request from anothernetwork entity, or when the UDM selects/determines the AMF to performthe UE reachability request, the UDM may transmit the UE reachabilitynotification request to the AMF by unconditionally selecting/determiningthe AMF which is serving 3GPP access with respect to the correspondingUE (when the steps S1600 and 1602 a are performed). This may beconstrued that the AMF related to 3GPP access is selected/determinedwhen there are a plurality of AMFs which are serving the UE.

Service/service operation information flow of Nudm_UEReachability_Notification service is shown in FIG. 17. In step S1701,the requester NF transmits UE reachability subscribe message forproviding information such as UE ID and Optional Parameters to the UDM.UE ID (for example, SUPI) should identify UE by the UDM. When theRequester NF transmits the UE Reachability Subscribe message, accesstype information may be included in this message. The access typeinformation may be included in this message only when the NF is the AMF.Also, the access type information may be included in the message only incase of non-3GPP access.

In step S1702, the UDM may selectively grant the requester on the basisof NF identities included in Optional Parameter. If the requester NF isnot granted to use this service, the UDM transmits Reject Response.

In step S1703, if the requester NF is granted to access this service,the UDM transmits UE Reachability Notify message to the requester NF assoon as it acquires that the UE is reachable. The UDM provides theRequester NF with reachability information of the UE on access typerelated to the access type information, that is, requested access type(or access type regarded to be requested) on the basis of the accesstype information included or not included in the request message. Atthis time, the access type information may be included in the response.For example, if the Requester NF is regarded to perform UE ReachabilitySubscribe for 3GPP access, the UDM detects that the UE is reachable on3GPP access and then reports the detected result to the Requester NF.

If the UDM receives the Subscribe message of step S1701, the UDM may beregarded to unconditionally subscribe UE reachability notificationservice for 3GPP access. This may be construed that it is assumed thatdetails on the access type information suggested in the step S1701 arenot added.

In this case, Nudm_UE Reachability_Notification may be specified aslisted in Table 7 below. In the following description, the scope of thepresent invention is not limited to a specific name, etc.

TABLE 7 Service name: Nudm_UE Reachability_Notification Description: TheRequester NF subscribes the service that once the UE becomes reachable,the requester NF can be notified by the UDM. Known NF Consumers: NEF.Concurrent use: No. Pre-requisite conditions: None Post conditions: NoneInputs, Required: UE ID Inputs, Optional: Optional Parameters. Outputs,Required: UDM Notify the Requester NF when the corresponding UE isreachable Outputs, Optional: None

Meanwhile, Service/service operation information flow ofNudm_Subscription Data_UpdateNotification service is shown in FIG. 18.In step S1801, the UDM transmits Subscriber Data Update Notification(SUPI, Subscription Data) message to the Requester NF previouslyregistered in the UDM through the previous Nudm_Serving NF_Registration.If there are a plurality of Requester NFs with respect to the UE (forexample, there are two serving AMFs with respect to the UE, wherein oneis AMF for 3GPP access and the other one is AMF for non-3GPP access),the UDM performs the operation of step S1801 for all of the RequesterNFs.

The UDM may perform the above operation to be suitable for the accesstype served by the AMF. That is, if subscriber information for aspecific access type is changed, the UDM may report the changedsubscriber information to the Requester NF related to the correspondingaccess type. At this time, the access type of which subscriberinformation is changed may be added to the Subscriber Data UpdateNotification message.

For example, if subscriber information for non-3GPP access is changed,the UDM may report the changed subscriber information to the AMF relatedto this access. This means that the report is not given to the AMFrelated to 3GPP access if the corresponding AMF exists. In this case,Nudm_Subscription Data_UpdateNotification may be specified as listed inTable 8 below. In the following description, the scope of the presentinvention is not limited to a specific name, etc.

TABLE 8 Service or service operation name: Nudm_SubscriptionData_UpdateNotification Description: The UDM notifies NF consumer of theupdates of UE's Subscriber Data. Known NF Consumers: AMF, SMF, SMSFConcurrent use: No. Pre-requisite conditions: UDM detects UE'ssubscription data is updated Post conditions: None. Inputs, Required:Serving NF registered in UDM implicitly/ explicitly for notification.Inputs, Optional: None. Outputs, Required: SUPI, Updated subscriptionData Outputs, Optional: None

UE Activity Notification procedure is shown in FIG. 19. Referring toFIG. 19, in step S1901, the AMF receives indication for UE reachability(for example, Registration Request message or Service Request messagefrom the UE, or UE Reachability Indication from RAN). The RAN may be3GPP access related RAN, or N3IWF.

In step S1902, if the AMF includes MM context of the UE, and URRP-AMFfor the UE is configured to immediately report if the UE is reachable,the AMF transmits UE-Activity-Notification (Permanent ID, UE-Reachable)message to the UDM (step S1902 a) or the SMSF (step S1902 b), and clearsthe corresponding URRP-AMF.

If the AMF manages the URRP-AMF parameter per access, and if theURRP-AMF for the access for which the UE is reachable is set to “set”, amessage reporting that the UE is active may be transmitted to an entity(e.g., UDM, SMSF, etc.) which has requested UE reachability notificationwith respect to the corresponding access. At this time, the message mayinclude an access for which the UE is reachable. However, even if themessage does not include information on the access, since the entitysuch as the UDM knows that the AMF is a serving AMF for a correspondingaccess, the entity may determine an access for which the UE isreachable. Afterwards, the AMF clears the URRP-AMF for the correspondingaccess.

In step S1903, if the UDM receives UE-Activity-Notification (PermanentID, UE-Reachable) message or Update Location message for a UE that hasURRP-AMF set, the UDM triggers proper notifications for entities thatsubscribe these notifications and clears the URRP-AMF for the UE.

If the UDM receives a report message indicating that the UE becomesactive, from the AMF, the UDM may transmit a message for reporting thatthe UE is active to the entity which has requested the UE reachabilitynotification with respect to the corresponding access (the method foridentifying the access is described in the step S1902). At this time,the message may include an access for which the UE is reachable. If theUDM manages URRP-AMF parameter per access, the UDM clears URRP-AMF foraccess for which the UE is reachable.

Meanwhile, 5GS to EPS handover for single-registration mode with Nxinterface procedure of 3GPP TS 23.502v0.3.0 is shown in FIG. 20. Nxinterface is an interface between AMF and MME for interaction of 5GS andEPS. Details of each step in FIG. 20 will be replaced with thedescription of 5GS to EPS handover for single-registration mode with Nxinterface of 3GPP TS 23.502v0.3.0.

The MME may perform Update Location operation together with HSS (thismay be construed as HSS+UDM, and may be referred to as UDM). This is tonotify the HSS that the MME has become a serving node for the UE.Therefore, the MME transmits the Update Location Request message to theHSS, and the HSS which has received the Update Location Request messageperforms a Cancel Location operation together with the AMF. The AMF inwhich the HSS performs the Cancel Location operation is the AMF relatedto 3GPP access. That is, if the UE performs handover from 5GS to EPS,cancel location by the HSS and the UDM may be performed for the AMF ofwhich access type is 3GPP. For example, if there are AMF #1 associatedwith 3GPP access with respect to the corresponding UE and AMF #2associated with non-3GPP access, the AMF performs the Cancel Locationoperation together with the AMF #1. (Details of the Cancel Location willbe understood with reference to the details described in theNudm_Serving NF_RemoveNotification service.)

Unlike the above case, if the MME transmits Update Location Requestmessage to the HSS, the HSS may keep the AMF related to 3GPP instead ofcancelling the AMF. The Update Location operation of the MME may becaused by TAU operation of the UE or not. (The Update Location operationand the Cancel Location operation in the EPS will be understood withreference to TS 29.272.)

The above description may extensively or equally be applied to anotherscenario in which the UE changes system from 5G system to EPS as well asthe shown procedure. Also, the above description may be applied to bothof the case that the UE changes the 5G system to the EPS in an idle modeand the case that the UE changes the 5G system to the EPS in a connectedmode. For example, if the UE which is in the idle mode (or if the UE ofthe idle mode) changes 5GS to the EPS, the UDM may perform the CancelLocation operation for the AMF of which access type is 3GPP, that is,may transmit a deregistration message to the AMF.

Also, the above description may be applied to both of the case that theUE is SR(Single Registered: registered in only one system) and the casethat the UE is DR(Dual Registered: registered in two systems). Also, theabove description may be applied to both of the case that there isinterface (Nx interface) between the 5G System and the EPS and the casethat there is no interface.

Meanwhile, EPS to 5GS handover using Nx interface procedure of 3GPP TS23.502v0.3.0 is shown in FIG. 21.

Referring to FIG. 21, in step S2101, source E-UTRAN determines that theUE should perform handover to 5G-RAN. The E-UTRAN transmits HandoverRequired (Target 5G-RAN Node ID, Source to Target Transparent Container)message to the MME.

In step S2102, the MME selects a target AMF, and transmits Nx RelocationRequest (Target 5G-RAN Node ID, Source to Target Transparent Container,EPS MM Context, PDN Connection info) message to the AMF.

When the MME selects the target AMF, the MME may query the HSS (this maybe construed as HSS+UDM, and may be referred to as UDM). If the servingAMF for the UE already exists, the HSS may provide the MME with theinformation indicating that the serving AMF exists. At this time, theHSS may be provided only if the serving AMF and the MME belong to thesame PLMN. Unlike this case, PLMN information may be provided to the MMEtogether with the serving AMF, whereby the PLMN information may be usedsuch that the MME may select/determine the target AMF. Also, the HSS mayprovide information (e.g., AMF ID) on the AMF even in the case that theserving AMF is AMF related to non-3GPP access. If the serving AMF forthe UE exists for 3GPP access and non-3GPP access, the HSS may provideserving AMF information related to the 3GPP access.

Details of the other steps S2103 to S2118 will be replaced with thedescription of 5GS to EPS handover for single-registration mode with Nxinterface of 3GPP TS 23.502v0.3.0.

Referring to FIG. 21, the AMF may perform Update Location operationtogether with UDM (this may be construed as HSS+UDM, and may be referredto as UDM). This is to notify the UDM that the AMF has become a servingnode for the UE. If the AMF performs the Update Location operation (orthe operation described in Nudm_Serving NF_Registration service of FIG.11) for the UDM, the UDM performs the Cancel Location operation togetherwith the MME. Unlike this case, the UDM may keep the MME instead ofcancelling the MME.

The above description may extensively or equally be applied to anotherscenario in which the UE changes system from 5G system to EPS as well asthe shown procedure. Also, the above description may be applied to bothof the case that the UE changes the 5G system to the EPS in an idle modeand the case that the UE changes the 5G system to the EPS in a connectedmode. Also, the above description may be applied to both of the casethat the UE is SR(Single Registered: registered in only one system) andthe case that the UE is DR(Dual Registered: registered in two systems).Also, the above description may be applied to both of the case thatthere is interface (Nx interface) between the 5G System and the EPS(interface between the MME and the AMF) and the case that there is nointerface.

Although the operation suggested as above has been described based onthat the NF (Network Function) is AMF, without limitation to this case,the other NFs (e.g., SMF, PCF, SMSF, etc.) may perform the operationsuggested in the present invention. In the aforementioned description,the network function, the network entity and the network node refer tothe same entity.

FIG. 22 is a diagram illustrating a configuration of a user equipmentand a network node device according to the preferred embodiment of thepresent invention.

Referring to FIG. 22, a UE 100 according to the present invention mayinclude a transceiver 110, a processor 120 and a memory 130. Thetransceiver 110 may be configured to transmit various signals, data andinformation to an external device and receive various signals, data andinformation from the external device. The UE 100 may be connected withthe external device through the wire and/or wireless. The processor 120may control the overall operation of the UE 100, and may be configuredto perform a function of operation-processing information to betransmitted to and received from the external device. The memory 130 maystore the operation-processed information for a predetermined time, andmay be replaced with a buffer (not shown). Also, the processor 120 maybe configured to perform a UE operation suggested in the presentinvention.

Referring to FIG. 22, the network node device 200 according to thepresent invention may include a transceiver 210, a processor 220, and amemory 230. The transceiver 210 may be configured to transmit varioussignals, data and information to an external device and to receivevarious signals, data and information from the external device. Thenetwork node device 200 may be connected with the external devicethrough the wire and/or wireless. The processor 220 may control theoverall operation of the network node device 200, and may be configuredto allow the network node device 200 to perform a function ofoperation-processing information to be transmitted to and received fromthe external device. The memory 230 may store the operation-processedinformation for a predetermined time, and may be replaced with a buffer(not shown). Also, the processor 220 may be configured to perform anetwork node operation suggested in the present invention. In detail, aUDM receives a message related to serving AMF registration of the UE,which includes access type information and ID (Identity) information,from a first AMF, and if a second AMF registered as a serving AMF of theUE, which corresponds to the access type information, exists, the UDMmay transmit a deregistration related message to the second AMF.

Also, the details of the aforementioned UE 100 and the aforementionednetwork node device 200 may be configured in such a manner that theaforementioned various embodiments of the present invention mayindependently be applied to the aforementioned UE 100 and theaforementioned network node device 200, or two or more embodiments maysimultaneously be applied to the aforementioned UE 100 and theaforementioned network node device 200, and repeated description will beomitted for clarification.

The aforementioned embodiments according to the present invention may beimplemented by various means, for example, hardware, firmware, software,or their combination.

If the embodiments according to the present invention are implemented byhardware, the method according to the embodiments of the presentinvention may be implemented by one or more application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), processors, controllers,microcontrollers, microprocessors, etc.

If the embodiments according to the present invention are implemented byfirmware or software, the method according to the embodiments of thepresent invention may be implemented by a type of a module, a procedure,or a function, which performs functions or operations described asabove. A software code may be stored in a memory unit and then may bedriven by a processor. The memory unit may be located inside or outsidethe processor to transmit and receive data to and from the processorthrough various means which are well known.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of theinvention should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein. It is also obvious to those skilled in the art thatclaims that are not explicitly cited in each other in the appendedclaims may be presented in combination as an embodiment of the presentinvention or included as a new claim by a subsequent amendment after theapplication is filed.

INDUSTRIAL APPLICABILITY

Although the aforementioned various embodiments of the present inventionhave been described based on the 3GPP system, the aforementionedembodiments may equally be applied to various mobile communicationsystems.

The invention claimed is:
 1. A method of performing, by a Unified DataManagement (UDM), procedure related to registration of an Access andMobility Management Function (AMF) in a wireless communication system,the method comprising: receiving, by the UDM and from a first AMF, afirst message related to serving AMF registration of a user equipment(UE), wherein the first message includes access type information andidentity (ID) information, and wherein the access type informationindicates one of 3rd Generation Partnership Project (3GPP) access ornon-3GPP access; and transmitting, by the UDM and to a second AMF, asecond message for deregistration of the second AMF registered as aserving AMF of the UE, wherein the second message is only transmitted ina first case among the first case and a second case, wherein the firstcase is related to that an access type of the first AMF is 3GPP accessand an access type of the second AMF is 3GPP access, and wherein thesecond case is related to that the access type of the first AMF isnon-3GPP access and the access type of the second AMF is 3GPP access. 2.The method according to claim 1, further comprising: storing, by the UDMin at least one computer memory, the access type information and the IDinformation, wherein the access type information and the ID informationare related to the first AMF.
 3. The method according to claim 1,further comprising: receiving, by the UDM and from a Network Function(NF) that is an AMF, a third message related to deletion of informationrelated to the NF from a UE context, wherein the third message comprisesthe access type information.
 4. The method according to claim 1, basedon the deregistration of the second AMF is due to a subscriptionwithdrawal, the second message includes the access type information, andan information related to the subscription withdrawn.
 5. The methodaccording to claim 1, further comprising: receiving, by the UDM and froma Network Function (NF), a fourth message requesting serving AMFinformation, wherein the fourth message includes the access typeinformation; and transmitting, by the UDM and to the NF, the serving AMFinformation.
 6. The method according to claim 1, further comprising:receiving, by UDM and from a Network Function (NF), a request to provideUE reachability information, wherein the request to provide UEreachability information includes the access type information.
 7. Themethod according to claim 1, wherein, based on performing a handoverfrom a 5G system (5GS) to an Evolved Packet System (EPS), a cancellocation operation is performed by the UDM and a Home Subscriber Server(HSS) for the second AMF of which access type is the 3GPP access.
 8. Themethod according to claim 1, wherein, based on the UE changing from a5GS to an EPS in an idle mode, a cancel location operation is performedby the UDM for the second AMF of which access type is the 3GPP access.9. The method according to claim 1, wherein the ID information includesa Subscription Permanent Identifier (SUPI) of the UE.
 10. A Unified DataManagement (UDM) apparatus configured to perform a procedure related toregistration of an Access and Mobility Management Function (AMF) in awireless communication system, the UDM apparatus comprising: atransceiver; at least one processor; and at least one computer memoryoperably connectable to the at least one processor and storinginstructions that, when executed, cause the at least one processor toperform operations comprising: receiving, by the UDM and from a firstAMF, a first message related to serving AMF registration of a userequipment (UE), wherein the first message includes access typeinformation and identity (ID) information, and wherein the access typeinformation indicates one of 3rd Generation Partnership Project (3GPP)access or non-3GPP access; and transmitting, by the UDM and to a secondAMF, a second message for deregistration of the second AMF registered asa serving AMF of the UE, wherein the second message is only transmittedin a first case among the first case and a second case, wherein thefirst case is related to that an access type of the first AMF is 3GPPaccess and an access type of the second AMF is 3GPP access, and whereinthe second case is related to that the access type of the first AMF isnon-3GPP access and the access type of the second AMF is 3GPP access.11. The UDM apparatus according to claim 10, wherein the operationsfurther comprise: storing, in at least one computer memory, the accesstype information and the ID information, wherein the access typeinformation and the ID information are related to the first AMF.
 12. TheUDM apparatus according to claim 10, wherein the operations furthercomprise: receiving, from a Network Function (NF) that is an AMF, athird message related to deletion of information related to the NF froma UE context, wherein the third message comprises the access typeinformation.
 13. The UDM apparatus according to claim 10, based on thederegistration of the second AMF is due to a subscription withdrawal,the second message includes the access type information, and aninformation related to the subscription withdrawn.
 14. The UDM apparatusaccording to claim 10, wherein the operations further comprise:receiving, from a Network Function (NF), a fourth message requestingserving AMF information, wherein the fourth message includes the accesstype information; and transmitting, to the NF, the serving AMFinformation.
 15. The UDM apparatus according to claim 10, wherein the IDinformation includes a Subscription Permanent Identifier (SUPI) of theUE.
 16. A method of performing, by a first Access and MobilityManagement Function (AMF), procedure related to registration of in awireless communication system, the method comprising: transmitting afirst message related to serving AMF registration of a user equipment(UE) to a Unified Data Management (UDM), wherein the first messageincludes access type information and identity (ID) information, whereinthe access type information indicates one of 3rd Generation PartnershipProject (3GPP) access or non-3GPP access, wherein the first message isused by the UDM for transmitting a second message for deregistration ofa second AMF registered as a serving AMF of the UE to the second AMF,wherein the second message is only transmitted in a first case among thefirst case and a second case, wherein the first case is related to thatan access type of the first AMF is 3GPP access and an access type of thesecond AMF is 3GPP access, and wherein the second case is related tothat the access type of the first AMF is non-3GPP access and the accesstype of the second AMF is 3GPP access.
 17. The method of claim 16,wherein the access type information and the ID information is to bestored in the UDM.
 18. The method of claim 16, wherein the secondmessage includes the access type information, and an information relatedto a subscription withdrawn, based on the deregistration of the secondAMF is due to the subscription withdrawal.
 19. The method of claim 16,wherein, based on a handover from a 5G system (5GS) to an Evolved PacketSystem (EPS), a cancel location operation is performed by the UDM and aHome Subscriber Server (HSS) for the second AMF of which access type isthe 3GPP access.
 20. The method of claim 16, wherein, based on the UEchanging from a 5GS to an EPS in an idle mode, a cancel locationoperation is performed by the UDM for the second AMF of which accesstype is the 3GPP access.